The Cancer Research Center is a program project within the Department of Radiation Therapy, Joint Center for Radiation Therapy, Harvard Medical School. It supports a variety of individual research projects devoted to fundamental mechanisms in multi-modality cancer therapy. These investigations include studies on bone marrow stem cells, mammalian cells in culture, mammalian cells resistant to chemotherapeutic agents, somatic cell genetics, tumor biology, the effect of misonidazole on response of tumor cells to radiation and drugs in vitro and in vivo, and control mechanisms responsible for the expression of radiation sensitivity. Thus, these projects span the study of interactions at the molecular through tissue and organismal levels and provide the focus for multi-disciplinary research directed to the improved management of human cancer.